The knee is a type of hinge joint formed by the tibia (shinbone), femur (thighbone), and patella (kneecap). The ends of the bones in the knee joint are covered with cartilage, a tough, lubricating tissue that helps provide smooth, pain-free motion to the joint.
In between the cartilage surfaces are menisci which function to protect and unload the cartilage surfaces. In the middle of the knee, the ACL (anterior cruciate ligament) and PCL (posterior cruciate ligament) serve to provide stability during more athletic type activities. Any injury to the structures of the knee can cause pain and dysfunction. Meniscal injuries can cause considerable swelling and sharp pain in the knee. ACL injuries can give a sense of instability to the knee.
Osteoarthritis, the most common form of arthritis, is a wear and tear condition that destroys joint cartilage, and it typically develops after years of constant motion and pressure in the joints. As the cartilage continues to wear away, bone begins to rub against bone, causing the irritation, swelling, stiffness, and discomfort commonly associated with arthritis.
